1. Field of the Invention
The present invention relates to a rack-holding device.
2. The Prior Art
Rack-holding devices for racks which hold disks, such as silicon wafers, are known. The known rack-holding devices simply have grooves and webs which are milled into the basic surface and into which the racks are placed. Furthermore, there is a sensor on this basic surface, which records that the rack has been placed into the rack-holding device or has left the device again. Racks of this nature are designed in such a way that they are able to accommodate twenty-five wafers horizontally above one another. These racks serve as storage containers and transport containers. In such racks, preferably silicon wafers are introduced into a polishing machine, from which a gripper picks them up in succession in order to subject time to a polishing process. The same happens in a measuring device in which they are checked for defects, as well as anywhere else where disks or silicon wafers are handled horizontally.
A drawback of these rack-holding devices is that the racks become tilted and warped therein, or the rack itself is warped, so that the gripper cannot pick up the wafers correctly, with the result that the valuable wafers are damaged or destroyed. Furthermore, the racks may bend, so that the sensor does not detect that there is a rack in the rack-holding device, and the corresponding polishing machine or measuring device does not start to work.
It is an object of the present invention to provide a device to overcome the drawbacks of the prior art, and in particular to arrange the racks, and thus the wafers, in a defined position.
The above object is achieved according to the present invention by providing a rack-holding device with an attachment surface, which device has at least two side guides and at least one stop. The stop is arranged in each case in front of the at least two side guides, and the two side guides are arranged parallel to and at a distance from one another. The two side guides are designed in such a way that they have a bearing surface at essentially the same height.